Electrocatalytic hydrogenation of acetonitrile to ethylamine in acid

Electrochemical hydrogenation of acetonitrile based on well-developed proton exchange membrane electrolyzers holds great promise for practical production of ethylamine. However, the local acidic condition of proton exchange membrane results in severe competitive proton reduction reaction and poor selection toward acetonitrile hydrogenation. Herein, we conduct a systematic study to screen various metallic catalysts and discover Pd/C exhibits a 43.8% ethylamine Faradaic efficiency at the current density of 200 mA cm−2 with a specific production rate of 2912.5 mmol g−1 h−1, which is about an order of magnitude higher than the other screened metal catalysts. Operando characterizations indicate the in-situ formed PdHx is the active centers for catalytic reaction and the adsorption strength of the *MeCH2NH2 intermediate dictates the catalytic selectivity. More importantly, the theoretical analysis reveals a classic d-band mediated volcano curve to describe the relation between the electronic structures of catalysts and activity, which could provide valuable insights for designing more effective catalysts for electrochemical hydrogenation reactions and beyond.

the plant is 200 tons of acetonitrile per day.Supplementary Table 1 summarize the price of input chemicals and products.The plant levelized cost model for processing per ton of acetonitrile at a current density of 200 mA cm -2 is shown in the Supplemental Fig. 17.Supplementary Fig. 17.Model used for calculating the techno-economic analysis of generating ethylamine from acetonitrile using electricity.Units are in US$ per ton of acetonitrile.
Calculated assumptions for the TEA of generating EA from AN.
1.The cost of capital include the electrolyzer, catalysts and membranes, and separation equipment.It is assumed that the cost of the electrolyzer is US $10,000/m 2 and the lifetime of plant is 10 years.The cost of the catalysts and membranes is 5% of the electrolyzer cost and the separation equipment is 10% of the electrolyzer cost.
2. Assuming a plant operating capacity factor of 0.8, indicating that the plant operates 19.2 h per day 3. Inputs: Acetonitrile, H2SO4, water, or H2.For anode HOR operation, with an electrolyte of 0.5 M H2SO4 and 8 wt% acetonitrile, 0.54 tons of sulfuric acid, 10.96 tons of water, and 0.1 tons of H2 are needed to process 1 ton of acetonitrile, yielding ethylamine (Note: For anode OER operation, with an electrolyte of 0.5 M H2SO4 and 8 wt% acetonitrile, 0.54 tons of sulfuric acid, and 10.96 tons of water are needed to process 1 ton of acetonitrile, yielding ethylamine and hydrogen.).4.During the operation of the electrolyzer, the FEs of ethylamine and H2 were 40% and 60%, respectively.(Obtained from PEM stability tests).
5. The cost of electricity consists of two parts: the cost of electricity for the electrolyzer and the separation equipment.Assume that the price of electricity is US $0.1/kWh.The cost of electricity for separation equipment is 30% of electrolyzer electricity costs.
6.Both operation and maintenance costs are assumed to be 10% of the capital cost.

Computational process
Note: For anode HOR operation, the consumption of hydrogen is meticulously accounted for.
The precise calculation process is outlined as follows:

Electricity costs
The total cost of electricity required to process each ton of acetonitrile： where  is the total charge,  is the Faraday constant, and  ( 4) is the number of transferred electrons.
The operating potential of the electrolyzer is 0.8 V.The power required to maintain the process is calculated as follows：
The mass of hydrogen required for converting 1 ton of acetonitrile is:

Profit
The products of the electrochemical acetonitrile hydrogenation process are ethylamine and hydrogen.Of these, 0.35 tons of ethylamine are obtained per ton of acetonitrile feedstock.
Therefore, the value of the product is calculated as： Ethylamine product value = Ethylamine cost × Ethylamine mass obtaine = $3500.00 Total profit per ton of AN = Ethylamine profit = $3500.00 Therefore, daily profit per ton AN can be calculated as: Daily Profit = Total Profit − Total Cost = $195.66/tonNote: For anode OER operation, the products are ethylamine and hydrogen.It is noted that the sole cost variation during calculation is the electrical expense, while all other costs remain consistent with prior computations.The specific calculation is described below:

Electricity costs
The total cost of electricity required to process each ton of acetonitrile：

Profit
The products of the electrochemical acetonitrile hydrogenation process are ethylamine and hydrogen.Of these, 0.35 tons of ethylamine are obtained per ton of acetonitrile feedstock.
Therefore, the value of the product is calculated as： Ethylamine product value = Ethylamine cost × Ethylamine mass obtaine = $3500.00 Hydrogen profit = Hydrogen cost × Hydrogen mass obtained = $456.00 The Faraday efficiency of hydrogen is 60%, so the mass of hydrogen is: Hydrogen mass =  ×    ℎ  ×  = 240 kg Hydrogen profit = Hydrogen cost × Hydrogen mass obtained = 277.4$/ton Therefore, the product value can be calculated as: Total profit per ton of AN = Ethylamine profit + Hydrogen profit = $3777.4 The daily energy consumption is calculated as： Energy use per day = P × Time in a day × Capacity facto = 271.99× 24 × 0.8 = 5222.20ℎ The daily cost of electricity for the electrolyzer is: Electrolyzer electricity per day = Energy use per day × Electricity per kWh Mass of ethylene glycol produce = 5222.2× 0.1 = $522.22The separation cost is 30% of the electrolysis cost and is obtained from the following equation: Separation costs = 522.22× 0.3 = $156.67Therefore, the total electricity cost is： Total electricity cost = Electrolyzer electricity + Separation costs = 522.22+ 156.67 = $678.892. Capital cost a.Electrolyzer cost.Based on the operating current density (200 mA cm -2 ), the obtained electrolyzer area is calculated based on the following formula： Area of electrolyse = 339988.4 0.2   #$ = 170.00 $ Therefore, the cost of the electrolyzer is calculated as follows： Cost of electrolyser = 170.00× 10000 = $1700000.00b.Total cost of catalyst and membrane Cost of catalyst and membrane = 1700000 × 0.05 = $ 85000

=
Cost of AN × Mass of AN + Cost of H $ SO % × Mass of H $ SO % + Cost of water × Mass of water + Input costs of Hydrogen × Hydrogen mass obtained = $1982.714. Operating costs are 10% of the capital costs and is calculated as: Operating costs = 535.62× 0.1 = $ 53.56 5. Maintenance costs are 10% of the capital cost and is calculated as: Maintenance costs = 535.62× 0.1 = $ 53.56 Therefore, the total costs is obtained by adding up the five components： Total costs = Input chemicals + Electricity cost + Capital cost + Operating cost + Maintenance cost = $3304.34 35 × 10 !"  where  is the total charge,  is the Faraday constant, and  (4) is the number of transferred electrons.The daily energy consumption is calculated as： Energy use per day = P × Time in a day × Capacity facto = 669.78× 24 × 0.8 = 12859.78ℎ The daily cost of electricity for the electrolyzer is: Electrolyzer electricity per day = Energy use per day × Electricity per kWh Mass of ethylene glycol produce = 12859.78× 0.1 = $1286.00The separation cost is 30% of the electrolysis cost and is obtained from the following equation: Separation costs = 1286.0× 0.3 = $385.80Therefore, the total electricity cost is： Total electricity cost = Electrolyzer electricity + Separation costs = 1286.0+ 385.8 = $1671.80Therefore, the total costs is obtained by adding up the five components： Total costs = Input chemicals + Electricity cost + Capital cost + Operating cost + Maintenance cost = $3841.25